History, Origins and Conceptual Basis
History
In the United Kingdom two socio-economic classifications (SECs) have been widely used in both official statistics and academic research: Social Class based on Occupation (SC, formerly Registrar General's Social Class) and Socio-economic Groups (SEG). In 1994 the Office of Population Censuses and Surveys, now part of the Office for National Statistics, commissioned the Economic and Social Research Council (ESRC) to undertake a Review of Government Social Classifications.
As a result of the Review, the ESRC recommended that a new SEC, the National Statistics Socio-economic Classification, replace both SC and SEG. Full details of the Review and its conclusions can be found elsewhere (see Rose and O'Reilly 1997 and 1998; Rose, O'Reilly and Martin 1997; Rose and Pevalin 2001).
The final phase of the Review involved rebasing the NS-SEC on the new Standard Occupational Classification 2000 which was published in June 2000. This resulted in some important changes to the NS-SEC from the interim version of NS-SEC previously published in Rose and O'Reilly, 1998.
Origins
The National Statistics Socio-economic Classification (NS-SEC) has been developed from a sociological classification that has been widely used in pure and applied research, known as the 'Goldthorpe Schema' (see Goldthorpe 1980/1987 and 1997; Erikson and Goldthorpe 1992). The decision to adopt the Goldthorpe classification as the basis for the NS-SEC was made because it is widely used and accepted internationally, is conceptually clear, and has been reasonably validated both in criterion terms as a measure and in construct terms as a good predictor of health and educational outcomes. NS-SEC improves on the Goldthorpe Schema in terms of more thorough validation.
NS-SEC has been constructed to measure employment relations and conditions of occupations. Conceptually these are central to delineating the structure of socio-economic positions in modern societies and helping to explain variations in social behaviour and other social phenomena.
It is important for users of the NS-SEC to understand its conceptual basis and what it is measuring. Only then will they be able to (a) use it correctly, (b) improve their explanation of results, and (c) investigate whether the classification continues to be valid. Of course, a clear conceptual basis does not remove all barriers to explaining what socio-economic differences mean. Not everything can be explained by what a classification directly measures, employment is not the only determinant of life chances.
However, a properly constructed and validated classification such as the NS-SEC removes at least one barrier to explanation. The NS-SEC was not designed to offer improved statistical associations over SC and SEG, but to improve the possibility of explaining associations. As the NS-SEC is measuring employment relations, such as aspects of work and market situations and of the labour contract, the user can more readily construct causal narratives that specify how the NS-SEC links to a range of outcomes via a variety of intervening variables (see Rose and O'Reilly 1998: 27-30; Rose and Pevalin 2000: 1123-1125).
Conceptual basis
The NS-SEC aims to differentiate positions within labour markets and production units in terms of their typical 'employment relations'. Among employees, there are quite diverse employment relations and conditions, they occupy different labour market and work situations. Labour market situations equate to source of income, economic security and prospects of economic advancement. Work situations refer primarily to location in systems of authority and control at work, although a degree of autonomy at work is a secondary aspect. The NS-SEC categories thus distinguish different positions (not persons) as defined by social relationships in the work place, for example by how employees are regulated by employers through employment contracts. Three forms of employment regulation are distinguished.
1. In a 'service relationship' the employee renders 'service' to the employer in return for 'compensation' in terms of both immediate rewards (salary) and long-term or prospective benefits (assurances of security and career opportunities). The service relationship typifies Class 1 and is present in a weaker form in Class 2.
2. In a 'labour contract' employees give discrete amounts of labour in return for a wage calculated on amount of work done or by time worked. The labour contract is typical for Class 7 and in weaker forms for Classes 5 and 6.
3. Intermediate forms of employment regulation that combine aspects from both forms (1) and (2) are typical in Class 3.
The classification also separately identifies categories for large employers in its operational version, and for small employers and the self-employed with no employees in both the operational and analytic versions.
